Biocompatible and biostable implantable medical device

ABSTRACT

The present invention is related to a biocompatible and biostable implantable medical device. The present invention can include an implantable medical device including an electro-mechanical component. The electro-mechanical component can be coated with various novel and nonobvious coating combinations designed to promote biocompatibility and biostability. One layer of the coating combinations can be a tie layer. Another layer of the coating combinations can be a layer formed on top of the tie layer, and having biocompatible and biostable properties.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/887,730, filed Sep. 22, 2010, which claims priority to and thebenefit of U.S. Provisional Patent Application No. 61/330,266, filed onApr. 30, 2010, the entire disclosures of which are incorporated hereinby reference.

FIELD

The present invention broadly relates to medical devices and morespecifically, to a biocompatible and biostable implantable medicaldevice.

BACKGROUND

There are numerous varieties of implantable medical devices, such asfluid filled surgical implants presently comprising, or which may in thefuture comprise, access ports, for hydraulically adjustable gastricbands.

An exemplary hydraulic adjustable gastric band comprises a salinesolution inside of one or more inflatable portions (e.g., siliconeshells) positioned on the stomach surface of the ring of the gastricband to adjust the gastric band through a variety of diameters. As theinflatable portion is inflated it reduces the stoma of the gastric bandand when the inflatable portion is deflated it increases the stoma ofthe gastric band. The saline solution is added to or removed from theinflatable portion via an access port fixed beneath the skin of thepatient in the abdomen on the rectus muscle sheath using a fine needleto find the right level of restriction.

An exemplary gastric band (hydraulic, hydraulic-mechanical hybrid, orotherwise) may additionally, or alternatively, comprise an access portcoupled with an override mechanism to rapidly remove fluid or gel fromthe implant in the event of an emergency.

Each of the foregoing implants, as well as others, comprise access portsthat may be candidates for various electronics based enhancements, e.g.,an access port fitted with a pressure sensor and/or an access port thattransmits a signal for easier detection of its location within the bodyof the patient.

Furthermore, incorporation of electronic components into such accessports has not been workable at least in part because ofbioincompatibility. More specifically, these enhancements and theassociated electronics have heretofore caused cytotoxicity and/or beencompromised by the body's interstitial fluids over time.

Spehr (U.S. Pat. No. 6,240,320) discloses that biocompatible materialsuch as diamond-like carbon, sapphire, parylene compounds, diamond, orlike materials may be used to coat an exterior of the electrode member.However, Spehr suffers from the drawback that it does not use, forexample, a tie layer to enhance adhesion of the biocompatible material.Furthermore, Spehr does not disclose that several types of coatings canbe used in conjunction with each other to address all of the essentialrequirements for a successful long-term function. Such requirements caninclude, for example, long-term biocompatibility (10+years), ability tocoat relatively uniformly and thoroughly over an abrupt topology in aconformal manner, provide a significant barrier against water moleculepenetration or transmission, utilize a deposition temperature and otherprocessing parameters which are not too harsh for the substrate materialand the electromechanical device being coated, non-conductivity of theportion of the coating that directly contacts an electrical equipment,and ability to stay attached to the substrate materials and retain itsmoisture barrier properties despite (i) abrasion caused by handlingduring assembly; (ii) thermal expansion and contraction during shippingand handling and then due to operation of the device after implantation;(iii) material aging; (iv) chemical interaction between adjacentmaterials; and (v) exposure to sterilization, such as heat, chemicals orradiation.

Adamis (U.S. Pat. No. 7,563,255) discloses coating devices contactingtissue or bio fluid with biocompatible material, such as,polyethyleneglycol, polyvinylchloride, polycarbonate, polysulfone,polytetrafluoroethylene, parylene, titanium or the like, prior toimplantation. However, Adamis suffers from the drawback that it does notuse, for example, a tie layer to enhance adhesion of the biocompatiblematerial. Furthermore, Adamis does not disclose that several types ofcoatings can be used as a multilayered combination to address all of therequirements listed above.

SUMMARY

In accordance with exemplary embodiments, the present invention providesfor a biocompatible and biostable medical device that addresses theneeds in the prior art.

In accordance with exemplary embodiments, the present invention providesfor a medical device, such as an access port configured to detect thepressure of a fluid within the implant. In accordance with otherexemplary embodiments, the present invention provides for various noveland nonobvious coating combinations designed to promote biostability andbiocompatibility of electro-mechanical components in the medicaldevices, including, but not limited to, those disclosed herein.

In one embodiment, the present invention is an access port for a gastricband including a housing, and an electro-mechanical component locatedwithin the housing, wherein the electro-mechanical component is coatedwith a coating combination.

In another embodiment, the present invention is an access port for agastric band including a penetrable septum defining an outer wall of ahousing, a conduit configured to provide fluid communication between thepenetrable septum and the gastric band, a pressure sensor in fluidcommunication with a fluid within the gastric band, and a printedcircuit board assembly connected to the pressure sensor, wherein theprinted circuit board assembly is coated with a coating combination.

In yet another embodiment, the present invention is an access port for agastric band including a penetrable septum defining an outer wall of ahousing, a conduit configured to provide fluid communication between thepenetrable septum and the gastric band, and a pressure sensor in fluidcommunication with a fluid within the gastric band, wherein the pressuresensor is coated with a coating combination.

In still another embodiment, the present invention is a method forprotectively coating a long term medical device including coating thelong term medical device with a tie layer, and coating the long termmedical device with a biostable and biocompatible material.

In one embodiment, the present invention is an implantable medicaldevice including an electro-mechanical component coated with a coatingcombination including a tie layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary embodiments of the present invention will be described inconjunction with the accompanying drawing FIGS. in which like numeralsdenote like elements and:

FIG. 1A illustrates an access port comprising a pressure sensoraccording to an embodiment of the present invention;

FIG. 1B illustrates a cross sectional view of an access port comprisinga pressure sensor according to an embodiment of the present invention;

FIG. 2 illustrates a printed circuit board assembly coated with variouslayers according to an embodiment of the present invention;

FIG. 3 illustrates a printed circuit board assembly coated with variouslayers according to an embodiment of the present invention;

FIG. 4 illustrates a printed circuit board assembly coated with variouslayers according to an embodiment of the present invention;

FIG. 5 illustrates an electro-mechanical component for a medical devicecoated with various layers according to an embodiment of the presentinvention; and

FIG. 6 depicts a process according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

In accordance with exemplary embodiments, the present inventioncomprises a biocompatible and biostable medical device, such as anaccess port for a gastric band. Persons skilled in the art will readilyappreciate that various aspects of the invention may be realized by anynumber of methods and devices configured to perform the intendedfunctions. Stated differently, other methods and devices may beincorporated herein to perform the intended functions. It should also benoted that the drawing FIGS. referred to herein are not all drawn toscale, but may be exaggerated to illustrate various aspects of theinvention, and in that regard, the drawing FIGS. should not be construedas limiting. Finally, although the present invention may be described inconnection with various medical principles and beliefs, the presentinvention should not be bound by theory.

By way of example, the present invention will be described primarilywith reference to hydraulically adjustable gastric bands. Nevertheless,persons skilled in the art will readily appreciate that the presentinvention advantageously may be applied to and one of the numerousvarieties of fluid filled surgical implants presently comprising, orwhich may in the future comprise, access ports. Similarly, while thepresent invention will be described primarily with reference to fluidfilled surgical implants, persons skilled in the art will readilyappreciate that the present invention advantageously may be applied toother medical devices, whether fluid or gel filled.

In accordance with exemplary embodiments, the present invention providesfor an access port configured to detect the pressure of a fluid withinthe implant.

At the outset, it should be noted that while the present invention willbe described primarily with reference to an access port, persons skilledin the art will readily appreciate that an access port is not necessaryfor detection of the pressure of a fluid within an implant. Stateddifferently, the diagnostic and therapeutic advantages associated withknowing the pressure of a fluid within an implant, as provided for bythe present invention, may be realized without fluid access to theimplant via an access port.

As seen in FIGS. 1A and 1B, a medical device, such as an access port 10including a pressure sensor 20, and a penetrable septum 30 is depicted.The penetrable septum 30 can be penetrated by a needle to allow fluid orgel to be added or removed from the access port 10. A conduit 40provides access to a fluid filled implant such that the addition orremoval of fluid to the access port 10 thereby adds or removes fluidfrom the fluid filled implant. The needle can be, for example, a fineneedle, a hypodermic needle, a Huber needle, or any other type of needlewhich can supply fluid or gel to the access port 10. In addition, atube, instead of a needle can be used. The access port 10 can beconnected, for example, to the fluid filled implant (not shown) and canbe used to supply or remove fluid or gel from the fluid filled implant.The fluid filled implant can be, for example, a gastric band, and/or abreast implant (not shown).

The access port can also optionally include a plate element 50 which ispositioned between the penetrable septum 30 and the pressure sensor 20.The positioning of the plate element 50 serves to prevent the needlefrom damaging the pressure sensor 20. The plate element 50 can beformed, for example, from titanium, stainless steel, or any other typeof material that can protect the pressure sensor 20 from damage.

A printed circuit board assembly (PCBA) 60 can be connected, forexample, to the pressure sensor 20. The PCBA 60 is configured totelemetrically relay a pressure value obtained from the pressure sensor20 to an external control unit. The pressure value can indicate, forexample, a pressure of the access port 10 and/or the fluid filledimplant. The pressure sensor 20 can also detect, for example, a fillvolume, a strain, and/or a linear measurement of the access port 10. Theaccess port 10 can also include, for example, a housing 70 which can,for example, define a cavity containing the pressure sensor 20, aportion of the conduit 40, the plate element 50, and/or the PCBA 60. Thepenetrable septum 30 can define, for example, an outer wall of thehousing 70.

The present invention provides for various novel and nonobvious coatingcombinations designed to promote biostability and/or biocompatibility ofelectro-mechanical components of the access port or other medicaldevices, including, but not limited to, those disclosed herein.

The term biostable or biostability can mean, for example, that animplantable device or object is capable of being in contact with livingtissues or organisms and still function within the expected performanceparameters. In one embodiment, a biostable object or implanted devicecan still function within the expected performance parameters, forexample, for 10 years or more while being in contact with the livingtissues or organisms.

The term biocompatible or biocompatibility can mean, for example, thatthe implantable device or object is capable of being in contact withliving tissues or organisms without causing harm to the living tissue orthe organism. In one embodiment, a biocompatible object can be, forexample, an object which meets the U.S. Pharmacopoeia (“USP”) Class VIrequirements. For example, the coating combination may be biocompatibleover an extended period of time, such as for 1, 2, 5, 10, 15, 20, ormore years.

In accordance with exemplary embodiments, the present invention providesfor coating combinations that isolate electro-mechanical components,including, but not limited to, printed circuit board assemblies,sensors, motors and other components typical to implantable medicaldevices, and/or components forming those objects listed above. Theelectro-mechanical components can be purely electrical components,purely mechanical components, or a hybrid of electrical and mechanicalcomponents.

In one embodiment, the coating combinations can be, for example, amultilayer coating.

Another exemplary coating combination may be able to coat relativelyuniformly and/or thoroughly, over electro-mechanical components with anabrupt topology. Such electro-mechanical components can be objects withvarious abrupt geometries and/or various surface chemistries and thermalexpansion properties such as a PCBA. Stated differently, an exemplarycoating combination is capable of conformal coating.

Yet another exemplary coating combination may be a barrier against watermolecule and other moisture penetration and/or transmission.Qualitatively, an exemplary coating combination may have a moisturevapor transmission rate (MVTR) roughly equivalent to that of titanium atapproximately 25 μm (0.001 inches) thickness. Or, stated in terms ofwater vapor transmission rate (WVTR), an exemplary coating combinationmay allow less than 0.001 g/m²/day. MVTR and WVTR are measures of thepassage of water vapor through a substance.

Exemplary coating combinations may remain attached to the substratematerial and/or the electro-mechanical component being coated and retainits moisture barrier properties despite: (i) abrasion caused by handlingduring assembly; (ii) thermal expansion and contraction during shipping,handling, and operation of the electro-mechanical component afterimplantation; (iii) material aging; (iv) chemical interaction betweenadjacent materials; and (v) exposure to sterilization such as heat,chemicals or radiation.

The deposition temperature and other processing parameters of otherexemplary coating combinations should not be too harsh for the substratematerial and the electro-mechanical component being coated.

Depending on the electro-mechanical component being coated, yet otherexemplary coating combinations may be non-conductive or conductive. Forexample, where the electro-mechanical components transmit or receive RFsignals, the coating combinations should not be an RF shield. However,the coating combinations may provide RF interference protection whereappropriate.

In one embodiment, the coating combination, along with its coatingprocess, may be reasonable in terms of cost, e.g., no more than the costof the underlying electro-mechanical component being coated.

In accordance with exemplary embodiments of the present invention, anexemplary coating combination may comprise one or more of the followinglayers depending on the desired coating combination characteristics: (i)parylene (e.g., Parylene P, or Parylene M); (ii) diamond like carbon(DLC); (iii) titanium nitride (TiN); (iv) titanium carbide or siliconnitride; (v) cyclo olefin copolymer (COC) or cyclo olefin polymer (COP);(vi) epoxy; (vii) silicone polymer (e.g., primarily resin based (Q or Tfunctional), linear polymer based, or a hybrid of both); (viii) glass;(ix) chloro-tri-fluoro-ethylene (CTFE) orpoly-chloro-tri-fluoro-ethylene (PCTFE); (x) poly-ether-ether-ketone orpolysulfone; (xi) acetal or polyoxymethylene (POM); (xii) polypropylene;(xiii) liquid crystal polymer (LCP); (xiv) ultra high molecular weightpolyethylene (UHMWPE); and (xv) fluoropolymer acrylate; and (xvi)synthetic diamond.

Exemplary methods of applying an exemplary coating combination comprisesone or more of the following steps: (i) testing the electro-mechanicalcomponent for functionality; (ii) plasma treating the external surfacesof the electro-mechanical component, e.g., to remove small contaminantsand/or enhance surface adhesion; (iii) packaging the electro-mechanicalcomponent in a particle free environment and package meeting the ISOclass 6, or better, ISO 14644-1 clean room standard (class 1000 underthe FED-STD-209E clean room standard); (iv) opening and handling thepackage under clean room conditions; (v) placing the electro-mechanicalcomponent in a coating chamber; and (vi) applying the coating(s).

In accordance with exemplary embodiments of the present invention, anexemplary coating combination may comprise one or more layers appliedwith chemical vapor deposition (CVD), physical vapor deposition (PVD),plasma enhanced chemical vapor deposition (PECVD), injection molding,compression molding, transfer molding, film forming, thermoforming,vacuum forming, or dipping. In addition, other types of layerapplications are possible, which can be used to deposit layers whichhave conformal properties, adhesive properties, biocompatibleproperties, and/or biostable properties.

What follows now are several materials used for coating combinations inaccordance with the present invention.

Parylene P is a Parylene variation with high penetration properties.However, Parylene P may not necessarily be optimized for moisturebarrier properties. In one embodiment, Parylene P can be, for example,Parylene HT produced by Specialty Coating Systems or Parylene diX Nproduced by Kisco Conformal Coating. Parylene M is a variation ofParylene with good moisture barrier properties. However, Parylene M maynot have the penetrative properties of Parylene P. In one embodiment,Parylene M can be, for example, Parylene C produced by Specialty CoatingSystems or Parylene diX D produced by Kisco Conformal Coating.

DLC can be a hard coating that can be applied with either a chemicalvapor deposition (CVD) or a physical vapor deposition (PVD) process. Inone embodiment, the CVD version of the DLC including the Plasma EnhancedCVD (PECVD) can be used due to its improved conformal characteristics.The CVD version of the DLC can require a lower process temperature,reducing a likelihood of damage to the electro-mechanical componentbeing coated. Generally, DLC can be applied as a first layer to medicaldevices, or electro-mechanical components of medical devices that do nothave abrupt topographies. In electro-mechanical components of medicaldevices that do have abrupt topographies, the abrupt topographies can besmoothed out by over-molding (COC/Epoxy, etc.) or undercoating with someother more conformal coatings (Parylene), before the DLC is applied.Alternatively, a DLC with improved conformal characteristics can beused, such as the PECVD.

TiN can be deposited using CVD or variations of the CVD, and isgenerally biocompatible and a good moisture barrier. Some versions ofTiN can be deposited in a CVD process with temperatures below 60° C.,which makes it safe for most electro-mechanical components. TiN can besomewhat conductive, and may be beneficial for electrostatic discharge(ESD) protection and electromagnetic interference (EMI) protection.

Titanium carbide, silicon nitride, and a number of metallic thincoatings can be used as moisture barriers due to their low processingtemperatures. Any biocompatibility issues can be addressed byover-coating. Their conductive properties may also be beneficial incertain applications, such as for electrostatic discharge (ESD)protection and electromagnetic interference (EMI) protection.

COC, COP, or epoxy may not be as thin as Parylene or DLC, but they canprovide good barriers against moisture migration. In addition, thisover-mold or coverage can also allow a flat surface to be formed overthe electro-mechanical component, even when the electro-mechanicalcomponent has an abrupt topography. The flat surfaces increases thelikelihood that a uniform DLC or Parylene overcoat can be formed. Theepoxy can be applied by a casting or pouring process, while the COC canbe applied using injection molding.

Silicone polymer materials may be primarily resin based (Q or Tfunctional), linear polymer based, or any combination of the two. Thesilicone polymer materials may be long term-term biocompatible and cansmooth out any abrupt topography in the electro-mechanical component. Inaddition, the silicone polymer materials can provide good adhesion tothe subsequent coating options such as Parylene and DLC.

Glass can be applied in a casting or over-mold process when the hightemperature of the molten glass does not damage the substrate or theelectro-mechanical component that it is coating. However, iftemperatures typically over 260° C. are not acceptable, a glassencapsulation process can be used. The glass encapsulation process caninclude, for example, shrinking a thin glass layer over theelectro-mechanical component, or making a two-part glass housing in acasting process, fitting them over the electro-mechanical component, andthen sealing the seams with a glass-to-glass sealing. Glass can providea good moisture barrier, and many grades of glass are biocompatible. Inaddition, glass can offer a relatively flat surface for further coatinglayers if necessary.

CTFE or PCTFE can have low friction, inertness, and improved moisturebarrier properties. In one embodiment, Aclar® RX by Honeywell® can beused. Although it may be difficult to injection mold the CTFE or PCTFE,the CTFE or PCTFE material can be applied as a film over theelectro-mechanical component such as through thermoforming. Inthermoforming, the film of the CTFE or PCTFE can be heated and pressuresealed, or adhesively bonded.

Poly-ether-ether-ketone (PEEK) and polysulfone film or resin can possessdesirable biocompatibility properties due to its long-term implantablegrades. Due to their high temperature requirements, PEEK and polysulfonefilm or resin may be suitable for high temperature electro-mechanicalcomponents, or electro-mechanical components which do not require thePEEK and polysulfone film or resin to be over-molded over theelectro-mechanical component. Although the PEEK and polysulfone film orresin may have reduced moisture barrier properties, they can bethermoformed over the electro-mechanical component, for example, tosmooth out the abrupt topography in preparation for a Parylene or DLClayer.

Although POM has reduced moisture barrier properties, it can havebiocompatible grades and can be injection molded, making it a goodchoice for reducing the abrupt topography in an over-mold.

Polypropylene can provide a good moisture barrier and can be injectionmolded at relatively low temperatures. Thus, polypropylene can bebeneficial for reducing the abrupt topography in an over-mold for theelectro-mechanical component while avoiding heat damage to theelectro-mechanical component. In addition it can be relatively low costfor any cost-sensitive applications. Any biocompatibility issues can beaddressed by over-coating the polypropylene layer with DLC or Parylenelayers.

LCP can be injection moldable and can penetrate tight areas. It can alsobe molded in thin sections over the electro-mechanical component due toits desirable rheological behavior during injection molding. Thus,although it may have reduced moisture barrier properties and reducedlong-term implantable qualities, the liquid crystal polymer may beeffective in reducing abrupt geometries in the electro-mechanicalcomponent.

Ultra high molecular weight polyethylene has good abrasion resistanceand relatively good moisture barrier properties. It can also belong-term biocompatible. The ultra high molecular weight polyethylenecan be compression molded instead of injection molded, and also appliedas a thin film similar to PCTFE, PEEK, or polysulfone, but does notrequire as high as a temperature as such materials for thermoforming.

Fluoropolymer acrylate coating is applied as a coating in a dippingprocess, where the electro-mechanical component is dipped into anorganic solvent containing fluoropolymer acrylate. This coating istypically used as protective barrier layer on the electro-mechanicalcomponent, such as when the electro-mechanical component is anelectrical component. Fluoropolymer acrylate can have relatively goodmoisture barrier properties.

In the coating combinations, a tie layer can also be used. The tie layercan be formed, for example, from a material which is conformal and hasgood adhesive properties. In one embodiment, the tie layer can be, forexample, AdPro Plus produced by Specialty Coating Systems.

In one embodiment, the coating combinations can include a first layerformed on top of an electro-mechanical component and which has conformaland/or adhesive properties. The first layer can be, for example, a tielayer. A second layer can be formed on top of the first layer. Thesecond layer can have biocompatible and biostable properties. The secondlayer can be, for example, the outermost layer which contacts the bodyof a patient. If the second layer does not have moisture barrierproperties, additional layers can be formed between the first layer andthe second layer with moisture barrier properties. In addition,additional layers can be formed between the first layer and the secondlayer with additional desirable properties.

What follows are coating combinations which use some of the materialslisted above, according to various embodiments of the present invention:

Coating Combination 1

Layer 1—Tie layer which enhances adhesion of Parylene.

Layer 2—Parylene P with crevice penetration properties at a thickness ofapproximately 10 μm to 100 μm.

Layer 3—Parylene M at a thickness of approximately 10 μm to 100 μm.

Coating Combination 2

Layers 1 through 3—same as coating combination 1.

Layer 4—DLC at a thickness of approximately 0.02 μm to 0.2 μm.

Coating Combination 3

Layer 1—Tie layer which enhances adhesion of Parylene.

Layer 2—Parylene P with crevice penetration properties at a thickness ofapproximately 10 μm to 100 μm.

Layer 3—Epoxy (cast as thin as possible to smooth out abrupttopographies).

Layer 4—Parylene M at a thickness of 10 μm to 100 μm.

Coating Combination 4

Layers 1 through 4—Same as coating combination 3.

Layer 5—DLC at a thickness of approximately 0.02 μm to 0.2 μm or more.

Coating Combination 5

Same as coating combination 3 but replace Epoxy with COC, applied in aninjection molding tool.

Coating Combination 6

Same as coating combination 4 but replace Epoxy with COC, applied in aninjection molding tool.

Coating Combination 7

Same as coating combination 5, but instead of COC, use any of glass,chloro-tri-fluoro-ethylene or poly-chloro-tri-fluoro-ethylene,poly-ether-ether-ketone or polysulfone, polyoxymethylene, polypropylene,liquid crystal polymer, ultra high molecular weight polyethylene, andfluoropolymer acrylate.

Coating Combination 8

Same as coating combination 6, but instead of COC, use any of glass,chloro-tri-fluoro-ethylene or poly-chloro-tri-fluoro-ethylene,poly-ether-ether-ketone or polysulfone, polyoxymethylene, polypropylene,liquid crystal polymer, ultra high molecular weight polyethylene, andfluoropolymer acrylate.

What follows now are several embodiments of coating combinationscomprising silicone polymer in accordance with the present invention. Inexemplary embodiments, silicone polymer is formulated to cure from aspecified uncured state to a specified cured state. The uncured statewould range from low to moderate viscosity (1-1000 cp), used to controlthe coating process, and the cured state would be in a range of hardness(Shore A 20-100). An exemplary cure mechanism is a platinum system, butother systems may be suitable as well, for example, a condensation orperoxide cure system.

Coating Combination 9

Layer 1—A low durometer (softer) silicone applied directly to thesubstrate in a relatively thicker (higher viscosity) coating.

Layer 2—Parylene, DLC, TiN, PCTFE film, and/or combinations of thematerials listed.

Coating Combination 10

Layer 1—A high durometer (firmer) silicone applied directly to thesubstrate in a relatively thinner (lower viscosity) coating.

Layer 2—Same as coating combination 9.

Coating Combination 11

Layer 1—A low durometer (softer) silicone applied directly to thesubstrate in a relatively thicker (higher viscosity) coating.

Layer 2—A high durometer (firmer) silicone applied directly to thesubstrate in a relatively thinner (lower viscosity) coating.

Layer 3—Same as coating combination 9.

Coating Combination 12

Layer 1—A primer or tie layer which may be composed of silicone prime(resin), or any other material designed to increase adhesion.

Layer 2—A low durometer (softer) silicone applied directly to thesubstrate in a relatively thicker (higher viscosity) coating.

Layer 3—A high durometer (firmer) silicone applied directly to thesubstrate in a relatively thinner (lower viscosity) coating.

Layer 4—Same as coating combination 9.

Coating Combination 13

Layer 1—Same as coating combination 1.

Layer 2—A low durometer (softer) silicone applied directly to thesubstrate in a relatively thicker (higher viscosity) coating.

Layer 3—A high durometer (firmer) silicone applied directly to thesubstrate in a relatively thinner (lower viscosity) coating.

Layer 4—Same as coating combination 9.

Coating Combination 14

Layer 1—A primer or tie layer which may be composed of silicone prime(resin), or any other material designed to increase adhesion.

Layer 2—A single layer of silicone formulated to provide necessary,mechanical, thermal, and chemical properties.

Layer 3—Same as coating combination 9.

Coating Combination 15

Layer 1—Same as coating combination 1.

Layer 2—A single layer of silicone formulated to provide necessary,mechanical, thermal, and chemical properties.

Layer 3—Same as coating combination 9.

Coating Combination 16

Layer 1—A layer of silicone with conformal and adhesive properties.

Layer 2—A layer including materials which have moisture barrierproperties, such as DLC, Parylene M, TiN, or PCTFE.

Layer 3—A layer of silicone with biocompatible and biostable properties.

For example, in one embodiment as seen in FIG. 2, a PCBA 60 can becoated by a layer 62 and/or a layer 64. The layer 62 and/or the layer 64can form, for example, the coating combinations 1-15. The layer 62 canbe, for example, the Layer 1 in the coating combinations 1 - 15. Thelayer 64 can be, for example, the other layers, in the coatingcombinations 1 - 15. The PCBA 60, which is coated, can also be seen inFIGS. 3 and 4. In FIGS. 3 and 4, all sensitive electro-mechanicalcomponents in the PCBA 60 are coated by a coating combination 66 exceptfor the sensing element which is already biocompatible and/or biostableby choice of its construction material or by a thin layer of coatingincluding but not limited to DLC or TiN. The sensing element can be, forexample, a pressure sensing element.

In addition, although a PCBA 60 is depicted in FIGS. 2, 3 and 4, anymedical device can be coated. The medical device can be, for example, anaccess port fitted with a pressure sensor which measures the pressure inthe saline solution, an access port that transmits a signal for easierdetection of its location in the body, a pump that controls an amount offluid in the gastric band, any long term medical device such as a devicewhich is implanted for a long term (e.g. 10 years or more) within abody, and/or any electro-mechanical components of the objects listedabove. In one embodiment, the medical device can also includeelectro-mechanical components and/or software for detecting breaches tothe coating combinations. The medical device can include, for example,an onboard diagnostic tool to detect such breaches to the coatingcombinations.

In one embodiment, electro-mechanical components of a medical device,such as a long term medical device, can be coated. For example, anelectro-mechanical component 80 of a long term medical device can becoated as seen in FIG. 5. The electro-mechanical component 80 can becoated with the layer 62 and/or the layer 64.

In one embodiment, the one or more coatings or layers may be applied tovarious implantable medical devices such as an access port, a breastimplant, a cardiac rhythm management device, a pacemaker, acardioverter, a defibrillator, a neurostimulator, an activity sensor, apressure sensor, a multi-sensor device, a drug delivery pump or device,a heart monitor, a respiratory monitor, an artificial kidney or otherartificial organs aside from the heart, orthopedic implants withelectronics incorporating stress, pressure or force sensors. In oneembodiment, the various implantable medical devices are medical deviceswhich may come in contact with interstitial body fluids, but do not comein contact with blood.

The foregoing disclosure is illustrative of the present invention and isnot to be construed as limiting the invention. Although one or moreembodiments of the invention have been described, persons skilled in theart will readily appreciate that numerous modifications could be madewithout departing from the spirit and scope of the present invention. Byway of mere example, persons skilled in the art will readily appreciatethat the novel and nonobvious coating combinations designed to promotebiostability described herein advantageously may be applied not just tosurgical implants, but to any device or device component havingbiostability as a design requirement. In sum, it should be understoodthat all such modifications are intended to be included within the scopeof the invention.

The terms “a,” “an,” “the,” and similar referents used in the context ofdescribing the present invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein is merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein isintended merely to better illuminate the present invention and does notpose a limitation on the scope of the present invention otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element essential to the practice of thepresent invention.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember may be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group may be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Certain embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically described herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

Furthermore, certain references have been made to patents and printedpublications throughout this specification. Each of the above-citedreferences and printed publications are individually incorporated hereinby reference in their entirety.

Specific embodiments disclosed herein may be further limited in theclaims using consisting of or consisting essentially of language. Whenused in the claims, whether as filed or added per amendment, thetransition term “consisting of” excludes any element, step, oringredient not specified in the claims. The transition term “consistingessentially of” limits the scope of a claim to the specified materialsor steps and those that do not materially affect the basic and novelcharacteristic(s). Embodiments of the invention so claimed areinherently or expressly described and enabled herein.

In closing, it is to be understood that the embodiments of the presentinvention disclosed herein are illustrative of the principles of thepresent invention. Other modifications that may be employed are withinthe scope of the present invention. Thus, by way of example, but not oflimitation, alternative configurations of the present invention may beutilized in accordance with the teachings herein. Accordingly, thepresent invention is not limited to that precisely as shown anddescribed.

What is claimed is:
 1. An access port for use in conjunction with agastric band, the access port comprising: a housing; and anelectro-mechanical component located within the housing, wherein theelectro-mechanical component is coated with a coating combination. 2.The access port of claim 1, wherein the gastric band is a hydraulicallyadjustable gastric band.
 3. The access port of claim 1 furthercomprising: a penetrable septum formed on the housing; and a conduitconfigured to carry fluid between the penetrable septum and aninflatable portion of the gastric band.
 4. The access port of claim 3,wherein the electro-mechanical component is a pressure sensor incommunication with a fluid within the gastric band and configured tomonitor a parameter of the fluid, generate a pressure value signal basedon the parameter, and communicate the pressure value signal to anexternal control unit via RF telemetry.
 5. The access port of claim 4,further comprising a plate element positioned between the penetrableseptum and the pressure sensor to guard the pressure sensor against aneedle damaging it.
 6. The access port of claim 1, wherein theelectro-mechanical component is a printed circuit board assembly.
 7. Theaccess port of claim 1, wherein the electro-mechanical component is amotor.
 8. The access port of claim 1 wherein the coating combinationincludes a tie layer.
 9. The access port of claim 1, wherein the coatingcombination comprises at least two different layers selected from thegroup consisting of parylene, diamond like carbon, titanium nitride,titanium carbide, silicon nitride, cyclo olefin copolymer, cyclo olefinpolymer, epoxy, silicone polymer, glass, chloro-tri-fluoro-ethylene,poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone, polysulfone,polyoxymethylene, polypropylene, liquid crystal polymer, ultra highmolecular weight polyethylene, fluoropolymer acrylate, and syntheticdiamond.
 10. The access port of claim 9, wherein the at least twodifferent layers are applied by one or more of chemical vapordeposition, physical vapor deposition, plasma enhanced chemical vapordeposition, injection molding, compression molding, transfer molding,film forming, thermoforming, vacuum forming, or dipping.
 11. The accessport of claim 1, wherein the coating combination is biocompatible for atleast 10 years.
 12. The access port of claim 1 wherein the coatingcombination includes a first layer having conformal and adhesiveproperties, and a second layer on top of the first layer havingbiocompatible and biostable properties.
 13. An access port for a gastricband comprising: a penetrable septum defining an outer wall of ahousing; a conduit configured to provide fluid communication between thepenetrable septum and the gastric band; a pressure sensor in fluidcommunication with a fluid within the gastric band; and a printedcircuit board assembly connected to the pressure sensor, wherein theprinted circuit board assembly is coated with a coating combination. 14.The access port of claim 13, wherein the coating combination comprisesat least two different layers selected from the group consisting ofparylene, diamond like carbon, titanium nitride, titanium carbide orsilicon nitride, cyclo olefin copolymer, cyclo olefin polymer, epoxy,silicone polymer, glass, chloro-tri-fluoro-ethylene,poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone, polysulfone,polyoxymethylene, polypropylene, liquid crystal polymer, ultra highmolecular weight polyethylene, fluoropolymer acrylate, and syntheticdiamond.
 15. The access port of claim 13 wherein the coating combinationincludes a tie layer.
 16. The access port of claim 15 wherein thecoating combination includes a layer formed on top of the tie layer, andwhich has biocompatible and biostable properties.
 17. The access port ofclaim 13 wherein the pressure sensor is coated with the coatingcombination.
 18. An access port for a gastric band comprising: apenetrable septum defining an outer wall of a housing; a conduitconfigured to provide fluid communication between the penetrable septumand the gastric band; and a pressure sensor in fluid communication witha fluid within the gastric band, wherein the pressure sensor is coatedwith a coating combination.
 19. The access port of claim 18, wherein thecoating combination comprises at least two different layers selectedfrom the group consisting of parylene, diamond like carbon, titaniumnitride, titanium carbide, silicon nitride, cyclo olefin copolymer,cyclo olefin polymer, epoxy, silicone polymer, glass,chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,poly-ether-ether-ketone, polysulfone, polyoxymethylene, polypropylene,liquid crystal polymer, ultra high molecular weight polyethylene,fluoropolymer acrylate, and synthetic diamond.
 20. The access port ofclaim 18 wherein the coating combination includes a tie layer.
 21. Theaccess port of claim 20 wherein the coating combination includes a layerformed on top of the tie layer, and which has biocompatible andbiostable properties.
 22. An implantable medical device comprising: anelectro-mechanical component coated with a coating combination includinga tie layer.
 23. The implantable medical device of claim 22, wherein thecoating combination comprises at least two different layers selectedfrom the group consisting of parylene, diamond like carbon, titaniumnitride, titanium carbide, silicon nitride, cyclo olefin copolymer,cyclo olefin polymer, epoxy, silicone polymer, glass,chloro-tri-fluoro-ethylene, poly-chloro-tri-fluoro-ethylene,poly-ether-ether-ketone, polysulfone, polyoxymethylene, polypropylene,liquid crystal polymer, ultra high molecular weight polyethylene,fluoropolymer acrylate, and synthetic diamond.
 24. The implantablemedical device of claim 22 wherein the coating combination includes alayer formed on top of the tie layer, and which has biocompatible andbiostable properties.
 25. A method for protectively coating a long termmedical device comprising: coating the long term medical device with atie layer; and coating the long term medical device with a biostable andbiocompatible material.
 26. The method of claim 25, wherein thebiostable and biocompatible material is selected from a group consistingof parylene, diamond like carbon, titanium nitride, titanium carbide,silicon nitride, cyclo olefin copolymer, cyclo olefin polymer, epoxy,silicone polymer, glass, chloro-tri-fluoro-ethylene,poly-chloro-tri-fluoro-ethylene, poly-ether-ether-ketone, polysulfone,polyoxymethylene, polypropylene, liquid crystal polymer, ultra highmolecular weight polyethylene, fluoropolymer acrylate, and syntheticdiamond.
 27. The method of claim 25 further comprising plasma treatingthe long term medical device.
 28. The method of claim 25 furthercomprising coating the long term medical device in a clean room meetingthe ISO class 6 ISO 14644-1 clean room standard.